immunoglobulin g high levelslow immunoglobulin g levelselevated immunoglobulin gimmunoglobulin g serum highimmunoglobulin g reference rangeimmunoglobulin g normal rangeimmunoglobulin g blood testlow immunoglobulin g serumimmunoglobulin g qn serum highimmunoglobulin g qn serum elevatedimmunoglobulin gimmunoglobulin g subclass 1